Synthesis of core-double-shell structured Fe3O4@PDA/HKUST-1: Characterization analysis and adsorption performance on cationic MB dyes

Organic dyes have complex and relatively stable molecular structures that are not easily removed in aqueous solutions. Methylene blue (MB) is a common toxic cationic organic dye. Therefore, in order to remove the excessive MB in wastewater, a novel magnetic core-double-shell structure of Fe3O4@PDA/HKUST-1 metal -organic framework material (MOF) using a two-step solvothermal method as an efficient adsorbent for MB. Various characterization techniques analyzed its morphology structure, porosity, magnetic stability, and thermal stability. The effects of initial pH, pollutant concentration, reaction time, and temperature on MB adsorption were investigated in detail by batch experiments. The results showed that the maximum adsorption capacity was up to 34 mg/g under the optimum adsorption conditions. The removal of MB followed the Langmuir isotherm and the pseudo-second-order model, which represented a thermodynamically spontaneous heat absorption process. Fe3O4@PDA/HKUST-1 had a good cyclic regeneration capacity. The results suggest that the adsorbent has wide application prospects.